Methods of fabricating integrated circuit devices including air spacers separating conductive structures and contact plugs

ABSTRACT

An integrated circuit device includes first and second conductive structures spaced apart from one another on a substrate along a first direction. The first and second conductive structures extend in a second direction substantially perpendicular to the first direction. A contact plug is interposed between the first and second conductive structures and is separated therefrom along the first direction by respective air gaps on opposite sides of the contact plug. The air gaps define first and second air spacers that electrically insulate the contact plug from the first and second conductive structures, respectively. An upper insulation layer covers the first and second air spacers and the first and second conductive structures. The air spacers may sufficiently reduce the loading capacitance between the conductive structures. Related fabrication methods are also discussed.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Korean Patent Application No.10-2009-0040800, filed on May 11, 2009, in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein in itsentirety by reference.

BACKGROUND

Example embodiments relate to integrated circuit devices and a method offabricating the same.

Generally, integrated circuit devices may include a multilayer structureof wiring lines in which the wiring lines are vertically stacked on asubstrate and electrically connected with each other by contact plugs.Recently, higher integration in integrated circuit devices has reducedthe gap distance between the wiring lines and the contact plugs. Assuch, integrated circuit devices may have an increased loadingcapacitance in the multilayered wiring structure. Higher loadingcapacitance in dynamic random access memory (DRAM) devices maysignificantly reduce the operational speed of the devices and/or maydeteriorate refresh characteristics of the devices.

SUMMARY

Example embodiments provide integrated circuit devices having reducedloading capacitance between conductive patterns thereof. Other exampleembodiments provide methods of fabricating such integrated circuitdevices.

According to some embodiments, an integrated circuit device includesfirst and second conductive structures spaced apart from one anotheralong a first direction. The first and second conductive structuresextend in a second direction substantially perpendicular to the firstdirection. A contact plug is interposed between the first and secondconductive structures and is separated therefrom along the firstdirection by respective air gaps on opposite sides of the contact plug.The air gaps define first and second air spacers that electricallyinsulate the contact plug from the first and second conductivestructures, respectively. An upper insulation layer covers the first andsecond air spacers and the first and second conductive structures.

In some embodiments, first and second upper spacers may be positioneddirectly above the first and second air spacers, respectively. The firstand second upper spacers may separate sidewalls of the contact plug fromsidewalls of the first and second conductive structures adjacentthereto. The first and second upper spacers may define an upper boundaryof the first and second air spacers therebelow.

In some embodiments, the first and second conductive structures mayrespectively include a conductive line extending in the seconddirection, and a hard mask pattern stacked on the conductive line. Thefirst and second upper spacers may be positioned on the sidewalls of thefirst and second conductive structures, respectively, and the sidewallsof the first and second conductive structures may be defined by therespective hard mask patterns thereof.

In some embodiments, the first and second upper spacers may include aconductive material and may be directly on the sidewalls of the contactplug to increase a surface area thereof.

In some embodiments, the first and second upper spacers may extend alongportions of the sidewalls of the first and second conductive structuresin the second direction, and the first and second upper spacers may bediscontinuous in the second direction.

In some embodiments, the first and second upper spacers may extend alonga portion of the sidewalls of the first and second conductive structuresin the second direction beyond the contact plug.

In some embodiments, portions of the first and second conductivestructures may extend beyond the contact plug in the second directionand may be spaced apart from one another along the first direction by asecond air gap. The upper insulation layer may provide an upper boundaryof the second air gap.

In some embodiments, portions of the first and second conductivestructures may extend beyond the contact plug in the second directionand may be spaced apart from one another by a second air gap along thefirst direction. An insulation interlayer may fill the second air gapbetween the portions of the first and second conductive structures thatextend beyond the contact plug.

In some embodiments, the upper insulation layer may be directly abovethe first and second air spacers and may define an upper boundary forthe first and second air spacers therebelow.

In some embodiments, an etch protection layer may extend on sidewalls ofthe first and second conductive structures. The etch protection layermay include portions that laterally extend in the first directionbeneath the first and second air spacers. The laterally extendingportions of the etch protection layer may define a lower boundary of thefirst and second air spacers thereabove.

According to further embodiments, a method of fabricating an integratedcircuit device includes forming first and second conductive structureson a substrate spaced apart from one another in a first direction andextending in a second direction substantially perpendicular to the firstdirection. A contact plug is formed between the first and secondconductive structures and is spaced apart therefrom in the firstdirection by respective air gaps on opposite sides of the contact plug.The air gaps define first and second air spacers that electricallyinsulate the contact plug from the first and second conductivestructures, respectively. An upper insulation layer is formed on thefirst and second air spacers and the first and second conductivestructures.

In some embodiments, first and second upper spacer may be formed abovethe first and second air spacers, respectively. The first and secondupper spacers may separate sidewalls of the contact plug from sidewallsof the first and second conductive structures adjacent thereto. Thefirst and second upper spacers may define an upper boundary of the firstand second air spacers therebelow.

In some embodiments, the contact plug may be formed by forming aninsulation layer on the substrate to cover the first and secondconductive structures. The insulation layer may be partially removed toform a contact hole through which sidewalls of the first and secondconductive structures are exposed. Sacrificial spacers may be formed inthe contact hole on the sidewalls of the first and second conductivestructures exposed through the contact hole, and the contact plug may beformed in the contact hole including the sacrificial spacers therein.Then, the sacrificial spacers may be at least partially removed from thesidewalls of the conductive structures such that the contact plug isspaced apart from the sidewalls of the first and second conductivestructures by the air gaps defining the first and second air spacers.

In some embodiments, the insulation layer may be removed from thesubstrate after forming the contact plug and before removing thesacrificial spacers.

According to still further embodiments, an integrated circuit deviceincludes a structure on a substrate, the structure including at leastone pad contact. A plurality of bit line structures are arranged on thestructure and spaced apart from one another along a first direction. Thebit line structures extend in a second direction substantiallyperpendicular to the first direction. A plurality of contact plugs arerespectively interposed between neighboring ones of the bit linestructures and spaced apart therefrom by first gaps along the firstdirection. The first gaps define air spacers that electrically insulatethe neighboring ones of the bit line structures from respective ones ofthe contact plugs therebetween. An upper insulation layer is provided onthe air spacers and the bit line structures.

In some embodiments, the structure may further include a transistor onthe substrate, a first insulation interlayer through which the padcontact extends, a second insulation interlayer on the first insulationinterlayer, and a bit line contact directly on the pad contact. The padcontact may extend through the first insulation interlayer to contactsource/drain regions of the transistor.

In some embodiments, at least one of the air spacers may extend from atop portion of a respective one of the contact plugs to a bottom portionof the respective one of the contact plugs.

In some embodiments, at least one of the air spacers may extend from atop portion of a respective one of the contact plugs but may not extendbeyond a bottom portion of one of the bit line structures adjacentthereto.

In some embodiments, an upper spacer may be positioned directly above arespective one of the air spacers and may separate a sidewall of arespective one of the contact plugs adjacent thereto from a sidewall ofa respective one of the bit line structures adjacent thereto. The upperspacer may define an upper boundary of the respective one of the airspacers therebelow.

In some embodiments, the bit line structures may respectively include abit line extending in the second direction, and a hard mask patternstacked on the bit line. The upper spacer may be positioned on thesidewall of the respective one of the bit line structures, and thesidewall of the respective one of the bit line structures may be definedby the hard mask pattern.

In some embodiments, the upper spacer may extend along an upper portionof the sidewall of the respective one of the bit line structures in thesecond direction, and the upper spacer may be discontinuous on thesidewall of the respective one of the bit line structures along thesecond direction.

In some embodiments, the upper spacer may be one of a solid insulatingmaterial and a conductive material.

In some embodiments, the upper spacer may extend along a portion of thesidewall of the respective one of the bit line structures along thesecond direction beyond the contact plug.

In some embodiments, the upper spacer may be an insulating material.

In some embodiments, portions of the neighboring ones of the bit linestructures may extend beyond the contact plugs in the second directionand may be spaced apart from one another by respective second gaps alongthe first direction. The second gaps may define respective air gapsbetween the portions of the neighboring ones of the bit line structures.

In some embodiments, portions of the neighboring ones of the bit linestructures may extend beyond the contact plugs in the second directionand may be spaced apart from one another in the first direction byrespective second gaps. An insulation interlayer may fill the respectivesecond gaps between the portions of the neighboring ones of the bit linestructures.

In some embodiments, an etch protection layer may cover sidewalls of thebit line structures and may include portions that laterally extend alongthe first direction beneath the air spacers. The laterally extendingportions of the etch protection layer may define a lower boundary of theair spacers thereabove.

In some embodiments, a capacitor may extend through the upper insulationlayer to contact at least one of the contact plugs.

In some embodiments, neighboring ones of the bit line structuresadjacent to each other in a peripheral region of the substrate may bespaced apart from each other by respective second gaps in the firstdirection. The second gaps may be filled with air and may definerespective air gaps between the neighboring ones of the bit linestructures in the peripheral region of the substrate.

In some embodiments, a method of fabricating an integrated circuitdevice includes forming a structure on a substrate, the structureincluding at least one pad contact. A plurality of bit line structuresare formed on the substrate and spaced apart from one another along afirst direction. The bit line structures extend in a second directionsubstantially perpendicular to the first direction. Respective contactplugs are formed between neighboring ones of the bit line structures andare spaced apart therefrom by first gaps in the first direction. Thefirst gaps define respective air spacers that electrically insulate theneighboring ones of the bit line structures from the respective contactplugs therebetween. An upper insulation layer is formed on the airspacers and the bit line structures.

In some embodiments, in forming the respective contact plugs, aninsulation layer may be formed on the substrate to cover the bit linestructures. The insulation layer may be partially removed to formcontact holes through which sidewalls of the bit line structures areexposed. Sacrificial spacers may be formed on the sidewalls of the bitline structures exposed through the contact holes, and the respectivecontact plugs may be formed in the contact holes including thesacrificial spacers therein. Then, the sacrificial spacers may be atleast partially removed from the sidewalls of the bit line structuressuch that the contact plugs and the sidewalls of the bit line structuresmay be spaced apart from each other by the first gaps to define the airspacers.

In some embodiments, in forming the contact plugs, an upper portion ofat least one of the sacrificial spacers may be removed to provide anupper gap space defined by a remaining portion of the at least one ofthe sacrificial spacers. An upper spacer may be formed in the upper gapspace. The upper spacer may separate an upper portion of a respectiveone of the contact plugs adjacent thereto from an upper portion of arespective one of the bit line structures adjacent thereto in such amanner that the respective one of the contact plugs may be enclosed orsurrounded by the upper spacer.

In some embodiments, the upper spacer may be one of a solid insulatingmaterial and a conductive material.

In some embodiments, the upper spacer may be a material having etchingselectivity with respect to the sacrificial spacers.

In some embodiments, in forming the contact plugs, the insulation layermay be removed from the substrate before removing the sacrificialspacers such that portions of the neighboring ones of the bit linestructures extending beyond the respective contact plugs in the seconddirection may be spaced apart from one another by respective second gapsalong the first direction. The second gaps may define respective airgaps between the portions of the neighboring ones of the bit linestructures.

In some embodiments, in forming the contact plugs, sacrificial spacersmay be formed on sidewalls of the bit line structures, and an insulationlayer may be formed on the substrate to a thickness sufficient to coverthe bit line structures. The insulation layer may be partially removedfrom the substrate to form contact holes through which portions of thesacrificial spacers are exposed, and the respective contact plugs may beformed in the contact holes such that the sacrificial spacers contactthe respective contact plugs. The sacrificial spacers may be at leastpartially removed such that the respective contact plugs and the bitline structures adjacent thereto may be spaced apart from one another bythe first gaps to define the air spacers between the contact plugs andthe bit line structures.

In some embodiments, in forming the contact plugs, an upper portion ofat least one of the sacrificial spacers may be removed to form an uppergap space defined by a remaining portion of the at least one of thesacrificial spacers, and an upper spacer may be formed in the upper gapspace. The upper spacer may extend on a sidewall of an upper portion ofa respective one of the bit line structures in the second direction. Theupper spacer may be an insulation material.

Thus, according to some example embodiments of the present inventiveconcept, an air spacer may be interposed between the contact plug andthe conductive structure and an air gap may be interposed betweenneighboring ones of the conductive structures adjacent to each other.Thus, due to the relatively low dielectric constant of the air spacers,a loading capacitance between the conductive structure and the contactplug may be reduced even though the conductive structure and the contactplug may be positioned relatively close to each other. In addition, theloading capacitance between the immediately adjacent ones of theconductive structures may also be reduced due to the air gaptherebetween.

As such, a signal speed may be improved in integrated circuit devicesaccording to some embodiments, and refresh characteristics and/oroperational speed of the integrated circuit devices may be improved dueto the reduction of the loading capacitance.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings.

FIG. 1 is a perspective view illustrating an integrated circuit devicein accordance with some embodiments of the present inventive concept;

FIG. 2 is a cross-sectional view taken along a line A-A′ in FIG. 1;

FIGS. 3 to 5 are cross-sectional view illustrating processing steps fora method of fabricating the integrated circuit device shown in FIG. 1;

FIG. 6 is plan a view illustrating of a dynamic random access memory(DRAM) device in accordance with further embodiments of the presentinventive concept;

FIG. 7A is a cross-sectional view take along a line A-A′ in FIG. 6;

FIG. 7B is a cross-sectional view taken along a line B-B′ in FIG. 6;

FIG. 7C is a cross-sectional view taken along a line C-C′ in FIG. 6;

FIG. 7D is a cross-sectional view illustrating a peripheral circuitregion of the DRAM device shown in FIG. 6;

FIG. 8 is a perspective view illustrating a bit line portion of the DRAMdevice shown in FIG. 6;

FIGS. 9A to 15D illustrate processing steps for a method of fabricatingthe DRAM device shown in FIGS. 6 to 8;

FIG. 16 is a perspective view illustrating bit line portion of a dynamicrandom access memory (DRAM) device in accordance with still furtherembodiments of the present inventive concept;

FIG. 17A is a cross-sectional view of the DRAM device shown in FIG. 16taken along a line A-A′ in FIG. 6;

FIG. 17B is a cross-sectional view of the DRAM device shown in FIG. 16taken along a line B-B′ in FIG. 6;

FIG. 17C is a cross-sectional view of the DRAM device shown in FIG. 16taken along a line C-C′ in FIG. 6;

FIGS. 18A to 20C illustrate processing steps for a method of fabricatingthe DRAM device shown in FIGS. 16 and 17A to 17C;

FIGS. 21A and 21B are cross-sectional views illustrating a dynamicrandom access memory (DRAM) device in accordance with yet furtherembodiments of the present inventive concept;

FIG. 22 is a plan view of the DRAM device shown in FIGS. 21A and 21B;

FIGS. 23A to 24A illustrate processing steps for a method of fabricatingthe DRAM device shown in FIGS. 21A-21B and 22;

FIG. 25A is cross-sectional view illustrating a dynamic random accessmemory (DRAM) device in accordance with other embodiments of the presentinventive concept;

FIG. 26 is a plan view illustrating the DRAM device shown in FIG. 25A;

FIGS. 27A to 29A illustrate processing steps for a method of fabricatingthe DRAM device shown in FIG. 25A;

FIG. 30A is cross-sectional view illustrating a dynamic random accessmemory (DRAM) device in accordance with still other embodiments of thepresent inventive concept;

FIG. 31A is cross-sectional view illustrating a dynamic random accessmemory (DRAM) device in accordance with yet other embodiments of thepresent inventive concept;

FIG. 32 is a perspective view illustrating a bit line structure of theDRAM device shown in FIG. 31A; and

FIGS. 33A to 35A illustrate processing steps for a method of fabricatingthe DRAM device shown in FIG. 31A.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Various example embodiments will be described more fully hereinafterwith reference to the accompanying drawings, in which some exampleembodiments are shown. The present invention may, however, be embodiedin many different forms and should not be construed as limited to theexample embodiments set forth herein. Rather, these example embodimentsare provided so that this disclosure will be thorough and complete, andwill fully convey the scope of the present invention to those skilled inthe art. In the drawings, the sizes and relative sizes of layers andregions may be exaggerated for clarity.

It will be understood that when an element or layer is referred to asbeing “on,” “connected to” or “coupled to” another element or layer, itcan be directly on, connected or coupled to the other element or layeror intervening elements or layers may be present. In contrast, when anelement is referred to as being “directly on,” “directly connected to”or “directly coupled to” another element or layer, there are nointervening elements or layers present. Like numerals refer to likeelements throughout. As used herein, the term “and/or” includes any andall combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, third,etc. may be used herein to describe various elements, components,regions, layers and/or sections, these elements, components, regions,layers and/or sections should not be limited by these terms. These termsare only used to distinguish one element, component, region, layer orsection from another region, layer or section. Thus, a first element,component, region, layer or section discussed below could be termed asecond element, component, region, layer or section without departingfrom the teachings of the present invention.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting of thepresent invention. As used herein, the singular forms “a,” “an” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. It will be further understood thatthe terms “comprises,” “comprising,” “includes,” and/or “including,”when used in this specification, specify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof.

Example embodiments are described herein with reference tocross-sectional illustrations that are schematic illustrations ofidealized example embodiments (and intermediate structures). As such,variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, example embodiments should not be construed as limitedto the particular shapes of regions illustrated herein but are toinclude deviations in shapes that result, for example, frommanufacturing. For example, an implanted region illustrated as arectangle will, typically, have rounded or curved features and/or agradient of implant concentration at its edges rather than a binarychange from implanted to non-implanted region. Likewise, a buried regionformed by implantation may result in some implantation in the regionbetween the buried region and the surface through which the implantationtakes place. Thus, the regions illustrated in the figures are schematicin nature and their shapes are not intended to illustrate the actualshape of a region of a device and are not intended to limit the scope ofthe present invention.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein. As described herein, a “spacer” or “upperspacer” may refer to any structure that electrically insulates oneconductive structure from another, while an “air spacer” refers to aninsulating structure in which air, in the absence of other insulatingmaterials, provides electrical insulation.

Hereinafter, example embodiments will be explained in detail withreference to the accompanying drawings.

Embodiment I

FIG. 1 is a perspective view illustrating an integrated circuit devicein accordance with some embodiments of the present inventive concept andFIG. 2 is a cross-sectional view taken along a line A-A′ in FIG. 1.

Referring to FIGS. 1 and 2, a plurality of conductive structures 15 maybe provided on a substrate 10 and each of the conductive structures 15may include a conductive pattern 12 and a hard mask pattern 14 on theconductive pattern 12.

In an example embodiment, the conductive pattern 12 may comprisesemiconductor material doped with impurities, metal material, metalnitride, metal silicide, etc. These may be used alone or in combinationsthereof. In the present example embodiment, the conductive pattern 12may include a single layer or a multilayer having at least two thinlayers stacked on the substrate 10, and may define a line extending in afirst direction.

An underlying structure (not shown) and an insulation interlayer (notshown) for covering the underlying structure may be further provided onthe substrate 10. In such a case, the conductive pattern 12 may beprovided on the insulation interlayer.

The hard mask pattern 14 may comprise silicon nitride and may have awidth substantially identical to that of the conductive pattern 12, andthus an upper surface of the conductive pattern 12 may be covered withthe hard mask pattern 14. Thus the conductive structure 15 including theconductive pattern 12 and the hard mask pattern 14 may have a firstlength L1 in the first direction.

An etch protection layer 16 may be positioned on an upper surface and asidewall of the hard mask pattern 14, a sidewall of the conductivepattern 12 and a portion of an upper surface of the substrate 10. Forexample, the etch protection layer 16 may comprise silicon nitride.Thus, the sidewall of the conductive pattern 12 may be protected from asubsequent etching process by the etch protection layer 16. However, noetch protection layer may be provided around the conductive structure 15in some embodiments.

An upper spacer 18 may be provided at an upper portion of the hard maskpattern 14 which may be covered with the etch protection layer 16. Thus,the upper spacer 18 may be extended downward from a top portion of thehard mask pattern 14 in a configuration such that a bottom portion ofthe upper spacer 18 may be higher than the upper surface of theconductive pattern 12.

At least one contact plug 20 may be interposed between neighboring ones(e.g., immediately adjacent ones) of the conductive structures 15. Inthe present example embodiment, an upper surface of the contact plug 20may be coplanar with an upper surface of the upper spacer 18 and theupper surface of the hard mask pattern 14 or the upper surface of theetch protection layer 16 (if provided).

Thus, the upper spacer 18 may be interposed between the conductivestructure 15, which may or may not be covered with the etch protectionlayer 16, and the contact plug 20. More particularly, an upper sidesurface of the contact plug 20 may be covered with the upper spacer 18and each of the upper spacers 18 making contact with the upper sidesurface of the contact plug 20 may be isolated from each other. Thus,the upper spacer 18 may be individually positioned on the upper portionof the hard mask pattern 14 independently from each other. The upperspacer may define an air spacer therebelow, as described in detail asfollows.

As shown in FIGS. 1 and 2, a first space S1 is positioned below theupper spacer 18 and is defined between the conductive structure 15 andthe contact plug 20. The first spacer S1 may provide a void (e.g.,without any kind of thin layers and merely filled with air), to therebyform an air spacer 30 under the upper spacer 18. In addition, thecontact plug 20 and the upper spacer 18 may have a second length L2 thatis much shorter than the first length L1 in the first direction, andthus a second spacer S2 is defined by the contact plug 20 and theneighboring conductive structures 15. The second spacer S2 may alsoprovide a void (e.g., without any kind of thin layers and merely filledwith air), to thereby form an air gap 22 between the conductivestructures 15. Thus, the air spacer 30 and the air gap 22 may beconnected to each other.

Accordingly, the conductive pattern 12 and the contact plug 20 may faceor may be separated from each other not by the medium of a highdielectric thin layer but by the medium of air having a relatively lowdielectric constant, thus reducing the potential for parasiticcapacitance between the conductive pattern 12 and the contact plug 20.As a result, the component of the loading capacitance caused by thefirst parasitic capacitance may be reduced between the conductivepattern 12 and the contact plug 20 (also referred to herein as a “first”parasitic capacitance or capacitor). In addition, the neighboringconductive structures 15 may face each other and may be separated fromeach other by the medium of air having low dielectric constant, thusreducing the potential for parasitic capacitance between the conductivepatterns 12 of the neighboring conductive structures 15 (also referredto herein as a “second” parasitic capacitance or capacitor). As aresult, the component of the loading capacitance caused by the secondparasitic capacitance may be reduced between the conductive patterns 12of the neighboring conductive structures 15.

An upper insulation layer 32 may be positioned on the contact plug 20,the upper spacer 18, the hard mask pattern 14 and the air gap 22.However, no upper insulation layer 32 may be filled into the air gap 22,to thereby maintain the shape of the air gap 22 despite of the upperinsulation layer 32.

According to an example embodiment of the integrated circuit device, theair spacer 30 may be interposed between portions of the contact plug 20and the conductive pattern 12 facing each other, to thereby reduce thecomponent of the loading capacitance caused by the first parasiticcapacitor between the conductive pattern 12 and the contact plug 20. Inaddition, the air gap 22 may be interposed between portions of theneighboring conductive structures 15 facing each other, to therebyreduce the component of the loading capacitance caused by the secondparasitic capacitor between the conductive patterns. For example, theintegrated circuit device may include a dynamic random access memory(DRAM) device, the conductive structure 15 may be a word line, and thecontact plug 20 may be a contact plug between the neighboring word linesin the DRAM device.

FIGS. 3 to 5 are cross-sectional views illustrating processing steps fora method of manufacturing the integrated circuit device shown in FIG. 1.

Referring to FIG. 3, a conductive layer (not shown) may be formed on thesubstrate 10. A hard mask pattern 14 may be formed on the conductivelayer in a line extending in the first direction. The conductive layermay be partially removed from the substrate 10 by an anisotropic etchingprocess using the hard mask pattern as an etching mask, to thereby formthe conductive structure 15 in which the hard mask pattern 14 may bestacked on the conductive pattern 12. Thus, the conductive structure 15may also be formed into a line-shaped pattern extending in the firstdirection.

The etch protection layer 16 may be optionally formed on the sidewallsand the upper surface of the conductive structure 15. No etch protectionlayer 16 may be formed on the sidewalls and the upper surface of theconductive structure 15 in accordance with some processing conditions.

An insulation interlayer (not shown) may be formed on the substrate 10to a sufficient thickness to cover the conductive structure 15, and thenthe insulation interlayer may be partially removed from the substrate 10by a planarization process until an upper surface of the conductivestructure 15 or an upper surface of the etch protection layer 16 may beexposed. Then, the insulation interlayer may be partially removed fromthe substrate 10 between the neighboring conductive structures 15 andthe etch protection layer 16 may also be removed from the substratebetween the neighboring conductive structures 15, to thereby form acontact hole 23 through which the upper surface of the substrate 10 andthe sidewalls of the neighboring conductive structures 15 may beexposed. For example, the contact hole 23 may be formed to have thesecond length L2 smaller than the first length L1 of the conductivestructure 5. When the etch protection layer 16 may be formed on thesidewalls of the conductive structure 15, a surface of the etchprotection layer 16 may be exposed through the contact hole 23.

A sacrificial layer (not shown) may be formed on the bottom andsidewalls of the contact hole 23, on the upper surface of the conductivestructure 15 that may be covered with the etch protection layer 16 ifnecessary and on an upper surface of the insulation interlayer. Forexample, the sacrificial layer may have etching selectivity with respectto the etch protection layer 16 and the hard mask pattern 14 as well asthe insulation interlayer. The sacrificial layer may comprise a materialthat may be easily dissolved in an etchant for a wet etching process.For example, the sacrificial layer may comprise silicon germanium.

The sacrificial layer may be partially removed by an anisotropic etchingprocess, to thereby form a preliminary sacrificial spacer 24 on thesidewalls of the contact hole 23.

Referring to FIG. 4, a contact plug 20 may be formed in the contact hole23 including the preliminary sacrificial spacer 24. Then, an upperportion of the preliminary sacrificial layer 24 may be removed to adepth in the third direction III, to thereby foam a sacrificial spacer24 a interposed between the contact plug 20 and the conductive structure15. Thus, a gap space (not shown) may be formed between an upper portionof the conductive structure 15 and an upper portion of the contact plug20 and between the upper portion of the contact plug 20 and the upperportion of the insulation interlayer.

An upper spacer 18 may be formed in the gap space between the upperportion of the conductive structure 15 and the contact plug 20 andbetween the upper portion of the conductive structure 15 and theinsulation interlayer. The upper spacer 18 may have etching selectivitywith respect to the sacrificial spacer 24 a and the insulationinterlayer.

Referring to FIG. 5, the insulation interlayer may be removed from thesubstrate 10 by a dry etching process or a wet etching process, tothereby form the air gap 22 between the neighboring conductivestructures 15. The sacrificial spacer 24 a may also be exposed to theair gap 22.

Thereafter, the sacrificial spacer 24 a may be removed from thesubstrate 10 by a wet etching process, to thereby form the air spacer 30under the upper spacer 18. In other words, the upper spacer 18 mayprovide an upper boundary for the air spacer 30.

Referring to again FIGS. 1 and 2, an upper insulation layer 32 may beformed on the contact plug 20 and the conductive structure 15 in such amanner that the air gap 22 is not filled by the upper insulation layer32. Therefore, the air gap 22 may still remain between the neighboringconductive structures 15 although the conductive structures 15 may becovered with the upper insulation layer 32.

Accordingly, the loading capacitance between the neighboring conductivestructures 15 may be sufficiently reduced.

Embodiment II

FIG. 6 is a plan view illustrating a lay out of a dynamic random accessmemory (DRAM) device in accordance with further embodiments of thepresent inventive concept. FIG. 7A is a cross-sectional view taken alonga line A-A′ in FIG. 6 and FIG. 7B is a cross-sectional view taken alonga line B-B′ in FIG. 6. FIG. 7C is a cross-sectional view taken along aline C-C′ in FIG. 6 and FIG. 7D is a cross-sectional view illustrating aperipheral circuit region of the DRAM device shown in FIG. 6. FIG. 8 isa perspective view illustrating a bit line portion of the DRAM deviceshown in FIG. 6. The DRAM devices in accordance with the remainingexample embodiments of the present inventive concept, which will bedescribed hereinafter, may have the same layout of the DRAM device shownin FIG. 6.

Referring to FIGS. 6 to 8, a substrate 200 including a plurality ofactive regions and a plurality of device isolation regions 204 may beprepared. Each of the active regions may be defined by the deviceisolation region 204 and thus may be isolated from each other on thesubstrate 200. The substrate 200 may be divided into cell regions inwhich memory cell structures may be positioned and peripheral regions inwhich various peripheral circuit patterns may be positioned.

MOS transistors may be arranged on the cell region of the substrate 200and each of the MOS transistors may include a gate insulation layer 206a, a gate electrode 206 b and source and drain regions or electrodes208. In the present example embodiment, a hard mask pattern 206 c may bepositioned on the gate electrode 206 b.

The gate electrode 206 b may be shaped into a line extending in a firstdirection and may function as a word line 206 in the MOS transistor.

A first insulation interlayer 210 may be formed on the substrate 200 toa sufficient thickness to cover the MOS transistors. First and secondpad contacts 212 a and 212 b may make contact with the source and drainelectrodes 208, respectively, penetrating through the first insulationinterlayer 210.

A second insulation layer 216 may be positioned on the first insulationlayer 210. A bit line contact 218 may make contact with the first padcontact 212 a in the second insulation layer 216.

A bit line 220 may be positioned on the second insulation layer 216 andmay make contact with the bit line contact 218. The bit line may extendin a second direction perpendicular to the first direction and maycomprise at least one of a semiconductor material doped with impurities,a metal, a metal nitride, a metal silicide and compositions thereof. Forexample, the bit line 220 may include a multi-layered structure in whicha polysilicon layer, a tungsten nitride layer and a tungsten layer maybe sequentially stacked on the second insulation layer 216.

A hard mask pattern 222 may be positioned on the bit line 220 and mayhave a line width that is substantially the same as that of the bit line220. Thus, the hard mask pattern 222 may function as a mask pattern forpatterning the bit line 220. For example, the hard mask pattern 222 maycomprise silicon nitride and may have a height greater than that of thebit line 220. Thus, a bit line structure 224 including the bit line 220and the hard mask pattern 222 may positioned on the second insulationlayer 216.

An etch protection layer 226 may be arranged on a sidewall of the bitline 220, a surface of the hard mask pattern 222 and an upper surface ofthe second insulation interlayer 216. Thus, the sidewall of the bit line220 may be protected from being etched in a subsequent process by theetch protection layer 226. For example, the etch protection layer 226may have a thickness of about 300 Å or less and may comprise a materialhaving etching selectivity with respect to the first and secondinsulation interlayers such as silicon nitride.

A storage node contact plug 240 may be positioned between neighboringbit line structures 224. That is, the storage node contact plug 240 maycontact the second pad contact 212 b penetrating through the secondinsulation interlayer 216 and may be spaced apart from the bit linestructure 224 by a first gap distance d1.

An upper spacer 244 may be interposed between the upper sidewall of thehard mask pattern 222 of the bit line structure 224 and an uppersidewall of the storage node contact plug 240. As similarly describedwith reference to FIG. 5, the upper spacer 244 may enclose the upperportion of the storage node contact plug 240 and make contact with theupper sidewall of the hard mask pattern 222. Thus, the upper spacers 244may be isolated from each other to thereby be electrically insulatedfrom each other.

The upper spacer 244 may comprise an insulation material or a conductivematerial. For example, the upper spacer 244 may comprise silicon nitrideor polysilicon. When the upper spacer 244 may comprise polysilicon, theupper spacer 244 may also function as a supplementary contact and thus asurface area of the storage node contact plug 240 may be enlarged at anupper portion thereof since the upper spacer 244 may electricallycontact the upper portion of the storage node contact plug 240.

A lower surface of the upper spacer 244 may be higher than an uppersurface of the bit line 220 of the bit line structure 224, and thus theupper spacer 244 may not be positioned on a sidewall of the bit line220.

A first space S1 positioned below the upper spacer 244 and definedbetween the storage node contact 240 and the bit line structure 224 mayprovide a void (e.g., without any kind of thin layers and merely filledwith air), to thereby form an air spacer 250 under the upper spacer 244.That is, spacer materials other than air may not be positioned on thesidewall of the bit line structure 224 in the first space S1 below theupper spacer 244. In the present example embodiment, the air spacer 250may vertically extend from a lower surface of the upper spacer 244 to alower portion of the storage node contact plug 240.

The bit line structure 224 may extend to a first length in the seconddirection, and the storage node contact 240 may have a second lengthsmaller than the first length. Thus, some portions of the bit linestructure 224 may face the storage node contact plug 240 and may bespaced apart therefrom by the first gap distance d1, while the otherportions of the bit line structure 224 may directly face the neighboringbit line structure 224 without the storage node contact plug 240therebetween, and may be spaced apart by a second gap distance d2. Thus,a second space or gap S2 defined between the neighboring bit linestructures 224 and the storage node contact 240 may provide a voidwithout any kind of thin layers and merely filled with air, to therebyform an air gap 246 between the neighboring bit line structures 224.Thus, the air spacer 250 and the air gap 246 may be interconnected toeach other.

Accordingly, the air spacer 250 and the air gap 246 may be interposedbetween the neighboring bit line structures 224, and thus the storagenode contact plug 240 and a pair of the neighboring bit line structures224 may be separated from each other by a medium of air having arelatively low dielectric constant. Thus, the potential for a firstparasitic capacitor to be formed between the bit line structure 224 andthe storage node contact plug 240 and/or the potential for a secondparasitic capacitor to be formed between the neighboring bit linestructures 224 may be reduced. As a result, the components of theloading capacitance due to the first parasitic capacitor between the bitline structure 224 and the storage node contact 240 and/or the secondparasitic capacitor between the neighboring bit line structures 224 mayalso be reduced.

In addition, the upper spacer 244 may be positioned on the sidewall ofthe hard mask pattern 222 of the bit line structure 224 but not on thesidewall of the bit line 220 of the bit line structure 224. Therefore,the upper spacer 244 may have little to no effect on the loadingcapacitance. Furthermore, the upper spacer 244 may improve stability ofthe DRAM cell structure in the MOS transistor.

As shown in FIG. 7D, the bit line structure 224 including the bit line220 and the hard mask pattern 222 may also be positioned in theperipheral region of the substrate 200. A spacer (not shown) or nospacer may be positioned on a sidewall of the bit line structure 224 inthe peripheral region of the substrate 200. Since contact plugs may notbe arranged between the neighboring bit line structures 224 on theperipheral region of the substrate 200, upper spacers may not beprovided in the peripheral region of the substrate 200, and thus airspacers may not be provided in the peripheral region of the substrate200. That is, the air gap 246 (without the air spacer 250) may beprovided between the neighboring bit line structures 224 in theperipheral region of the substrate 200.

An upper insulation layer 252 may be positioned on the storage nodecontact 240, the upper spacer 244, the hard mask pattern 222 and the airgap 246. The upper insulation layer 252 may not fill or otherwise extendinto the air gap 246, to thereby maintain the air gap 246 as confined bythe upper insulation layer 252. For example, the upper insulation layer252 may comprise silicon nitride in some embodiments.

A capacitor 254 may penetrate through the upper insulation layer 242 andmay make electrical contact with the storage node contact 240. Forexample, the capacitor 254 may be shaped into a cylinder and include acylindrical lower electrode 254 a, a dielectric layer 254 b on a surfaceof the lower electrode 254 a and an upper electrode 254 c.

According to an example embodiment of the DRAM device shown in FIGS. 6to 8, the first space between the bit line 220 and the storage nodecontact 240 may be filled up with a low-k material having a lowerdielectric constant, such as air, in place of a high-k material having ahigher dielectric constant. Thus, the loading capacitance may be reducedbetween the bit line 220 and the storage node contact 240. Further, theair gap 246 may be interposed between the neighboring bit lines 220 inthe cell region and/or in the peripheral region of the substrate 200, tothereby reduce the loading capacitance between the neighboring bit linesin the DRAM device.

Accordingly, the loading capacitance may be significantly reduced in theDRAM device without increasing the gap distance between the bit line 220and the storage node contact plug 240, to thereby efficiently increasethe integration degree of the DRAM device. The reduction of the loadingcapacitance may improve the electronic characteristics of the DRAMdevice, such as the refresh period and/or the operational speed.

FIGS. 9A to 15D illustrate processing steps for a method ofmanufacturing the DRAM device shown in FIGS. 6 to 8.

In FIGS. 9A to 15D, the capital letter ‘A’ in each FIG. number indicatesa cross-sectional view cut along the line A-A′ in FIG. 6 and the capitalletter ‘B’ in each FIG number indicates a cross-sectional view cut alongthe line B-B′ in FIG. 6. In addition, the capital letter ‘C’ in eachFIG. number indicates a cross-sectional view cut along the line C-C′ inFIG. 6 and the capital letter ‘D’ in each FIG. number indicates across-sectional view illustrating a peripheral circuit region of theDRAM device. FIG. 14 is a perspective view illustrating the bit line ofthe DRAM device including the air gap.

Referring to FIGS. 9A to 9C, a pad oxide layer (not shown) and a firsthard mask layer (not shown) may be formed on the substrate 200. Then,the pad oxide layer and the first hard mask layer may be patterned intoa pad oxide pattern (not shown) and a first hard mask pattern (notshown). The substrate 200 may be partially etched by an etching processusing the first hard mask pattern as an etching mask, to thereby form adevice isolation trench 202 on the substrate 200.

An insulation layer (not shown) may be formed on the substrate 200 to asufficient thickness to fill up the device isolation trench 202 and maybe polished by a planarization process, to thereby by form a deviceisolation pattern 204. Accordingly, an active region on which variousconductive structures may be defined by the device isolation pattern 204and isolated from each other on the substrate 200. Accordingly, thesubstrate 200 may be divided into the active region and a deviceisolation region on which the device isolation pattern 204 may beformed.

A gate structure including a gate insulation layer 206 a, a gateelectrode 206 b and a hard mask pattern 206 c may be formed on theactive region of the substrate 200. Then, a spacer (not shown) may beformed on the sidewalls of the gate structure. Impurities may beimplanted into surface portions of the substrate 200 adjacent to thegage electrode 206 b, to thereby form the source and drain electrodes orregions 208 around the gate electrode 206 b. Thus, a plurality of MOStransistors may be arranged on the substrate 200. The gate electrode 206b may be formed into a line extending in the first direction and mayfunction as a word line of the MOS transistor.

A first insulation interlayer 210 may be formed on the substrate 200 toa sufficient thickness to cover the MOS transistors. The firstinsulation interlayer 210 may be partially removed from the substrate200 by an etching process, to thereby form a first contact hole (notshown) through which the source and drain electrodes 208 may be exposed.Conductive materials may be filled into the first contact holes, tothereby form first and second pad contacts 212 a and 212 b makingcontact with the source and drain electrodes 208, respectively.

The second insulation interlayer 216 may be formed on the firstinsulation interlayer 210. Then, the second insulation interlayer 216may be partially removed from the first insulation interlayer 210 by anetching process, to thereby form a second contact hole (not shown)through which the first pad contact 212 a may be exposed. Conductivematerials may be filled into the second contact holes, to thereby formthe bit line contact pad 218 making electrical contact with the firstpad contact 212 a.

The bit line structure 224 in which the bit line 220 and the hard maskpattern 222 may be stacked may be formed on the second insulationinterlayer 216 in such a manner that the bit line 220 may makeelectrical contact with the bit line contact pad 218. More particularly,a bit line conductive layer (not shown) and a hard mask layer (notshown) may be sequentially formed on the second insulation interlayer216. For example, the hard mask layer may be formed by a chemical vapordeposition process and may comprise silicon nitride.

For example, the hard mask layer may be formed to be thicker than thebit line conductive layer. The hard mask layer may be patterned into ahard mask pattern 222 extending in a second direction substantiallyperpendicular to the first direction. Then, the bit line conductivelayer may be partially removed from the second insulation interlayer 216by an etching process using the hard mask pattern as an etching mask, tothereby form the bit line 220 on the second insulation interlayer 216.Therefore, the bit line 220 and the hard mask pattern 222 may besequentially stacked on the second insulation interlayer 216, to therebyform the bit line structure 224 on the second insulation interlayer 216.Although not shown in figures, the bit line structure 224 may also beformed on the peripheral region of the substrate 200.

The etch protection layer 226 may be formed on an upper surface of thesecond insulation interlayer 216 and on sidewalls and an upper surfaceof the bit line structure 224. The sidewalls of the bit line structure224 may thereby be sufficiently protected from being etched in asubsequent process by the etch protection layer 226. The etch protectionlayer 226 may comprise a material having etch selectivity with respectto the second insulation interlayer 216 such as silicon nitride.However, in some embodiments, the etch protection layer may not beprovided around the bit line structure 224 and on the second insulationinterlayer 216 for process simplification.

Referring to FIGS. 10A to 10C, a third insulation interlayer 236 may beformed on the second insulation interlayer 216 to a sufficient thicknessto cover the bit line structure 224.

Then, the third insulation interlayer 236, the etch protection layer 226and the second insulation interlayer 216 may be sequentially removedfrom the substrate 200 by a photolithography process, to thereby form athird contact hole 232 through which the second pad contact 212 b may beexposed between the bit line structures 224. However, the third contacthole 232 may not be formed on the peripheral region of the substrate200.

More particularly, a photo mask pattern for the photolithography processfor forming the third contact hole 232 may be formed into a line havinga length different from that of the bit line structure 224 in the seconddirection, and thus a first portion of the sidewall of the bit linestructure 224, which may be covered with the etch protection layer 226,may be exposed through the third contact hole 232 after thephotolithography process. In contrast, a second portion of the sidewallof the bit line structure 224 may still be covered with the thirdinsulation interlayer as shown in FIGS. 10B and 10C.

Then, a sacrificial layer (not shown) may be formed on sidewall andbottom of the third contact hole 232, an upper surface of the bit linestructure 224 and on an upper surface of the third insulation interlayer236. For example, the sacrificial layer may comprise a material havingetching selectivity with respect to the etch protection layer 226 andthe hard mask pattern 222 as well as with respect to the second andthird insulation interlayers 216 and 236. The sacrificial layer maycomprise a material that may be easily dissolved in an etchant for a wetetching process. For example, the sacrificial layer may comprise silicongermanium.

The sacrificial layer may be partially removed by an anisotropic etchingprocess, to thereby form a preliminary sacrificial spacer 234 on thesidewalls of the third contact hole 232. A thickness of the preliminarysacrificial spacer 234 may define the thickness of an air spacer in asubsequent process between the bit line structure 224 and the storagenode contact 240, and thus the preliminary sacrificial spacer 234 may beformed to have a sufficient thickness in view of the thickness of theair spacer to be formed.

Referring to FIGS. 11A to 11C, a conductive layer (not shown) may beformed on the third insulation interlayer 236 to a sufficient thicknessto fill up the third contact hole 232. Then, the conductive layer may bepartially removed from the third insulation interlayer 236 by aplanarization process until the upper surface of the third insulationinterlayer 236 may be exposed.

Therefore, the conductive layer merely remains in the third contact hole232, to thereby form the storage node contact 240 making contact withthe second pad contact 212 b in the third contact hole 232. That is, thepreliminary sacrificial spacer 234 may be interposed between the bitline structure 224 and the storage node contact 240 while an uppersurface of the preliminary sacrificial spacer 234 may exposed.

Referring to FIGS. 12A to 12C, an upper portion of the preliminarysacrificial layer 234 may be removed downward to a depth, to therebyform a sacrificial spacer 234 a interposed between the bit linestructure 224 and the storage node contact 240. Thus, a gap space 242may be formed between an upper portion of the bit line structure 224 andan upper portion of the storage node contact 240 and between the upperportion of the storage node contact 240 and the third insulationinterlayer 236. That is, an upper surface of the sacrificial spacer 234a may be exposed through the gap space 242. In the present exampleembodiment, the removal of the preliminary sacrificial layer 234 may beperformed by a wet etching process, thereby reducing and/or minimizingdamage to neighboring structures and patterns around the preliminarysacrificial layer 234.

For example, the upper surface of the sacrificial spacer 234 a may behigher than the upper surface of the bit line 220. Since the upperspacer may be formed in the gap space 242 of which the bottomcorresponds to the upper surface of the sacrificial spacer 234 a in asubsequent process, the bottom of the upper spacer may be formed to behigher than the upper surface of the bit line 220.

Referring to FIGS. 13A to 13C, an upper spacer layer (not shown) may beformed on the third insulation interlayer 236, the storage node contact240 and the bit line structure 224. The upper spacer layer may comprisea material having etching selectivity with respect to the sacrificialspacer 234 a and the third insulation interlayer 236. For example, theupper spacer layer may comprise an insulation material such as siliconnitride or a conductive material such as polysilicon.

Then, the upper spacer layer may be planarized by a planarizationprocess such as a chemical mechanical polishing (CMP) process or anetch-back process until the storage node contact 240, the bit linestructure 224 and the third insulation interlayer 236 may be exposed.Thus, the upper spacer layer may remain in the gap space 242, to therebyform the upper spacer 244 between the upper portion of the bit linestructure 224 and the storage node contact 240 and between the upperportion of the bit line structure 224 and the third insulationinterlayer 236. That is, the upper spacer 244 may be shaped into a ringenclosing or surrounding the upper portion of the storage node contact240. In addition, the upper spacer 244 may be interposed between theupper sidewall of the hard mask pattern 222 and the upper sidewall ofthe storage node contact 240, and thus the upper spacer 244 may contactboth the hard mask pattern 222 and the storage node contact 240 at thefirst portion of the sidewall of the bit line structure 224. Incontrast, since the second portion of the sidewall of the bit linestructure 224 extending beyond the storage node contact 240 may still becovered with the third insulation interlayer, the upper spacer may notbe formed between the neighboring bit line structures 224. Therefore,the upper spacer 244 may be discontinuously formed on the upper sidewallof the hard mask pattern 222 of the bit line structure 224 in the seconddirection.

In case that the upper spacer 244 may comprise an insulation material,the upper spacer 244 may fill up the gap space 242 between the upperportion of the storage node contact 240 and the upper portion of the bitline structure 224. In contrast, in case that the upper spacer 244 maycomprise a conductive material such as polysilicon, the upper spacer 244may also function as a supplementary contact and thus a surface area ofthe storage node contact 240 may be enlarged at an upper portion thereofsince the upper spacer 244 may electrically contact the upper portion ofthe storage node contact 240.

FIG. 14 is a perspective view illustrating the bit lines of a DRAMdevice including an air gap according to some embodiments.

Referring to FIG. 14, the third insulation interlayer 236 may be removedfrom the substrate 200 by a dry etching process or a wet etchingprocess, to thereby form the air gap 246 between the neighboringconductive structures 224. When the third insulation interlayer 236 maybe removed by a dry etching process, the plasma process for the dryetching process may cause damage to the bit line structure 224. For thatreason, the third insulation interlayer 236 may be removed from thesecond insulation interlayer 216 by a wet etching process in someembodiments. In the above wet etching process, the etch protection layer226 may function as an etch stop layer and thus the third insulationinterlayer 236 may be removed from the substrate 200 without substantialremoval of the second insulation interlayer 216.

As a result of the removal of the third insulation interlayer 236, thesacrificial spacer 234 a may be exposed to the air gap 246. In otherwords, the sacrificial spacer 234 a may define a boundary of the air gap246.

Referring to FIGS. 15A to 15D, the sacrificial spacer 234 a may beremoved from the substrate 200 by a wet etching process, to thereby formthe air spacer 250 between the storage node contact 240 and the bit linestructure 224. The air spacer 250 may be connected to (e.g., in fluidcommunication with) the air gap 246.

Accordingly, the air spacer 250 may be interposed between the storagenode contact 240 and the first portion of the sidewall of the bit linestructure 224 and between the storage node contact 240 and the secondinsulation interlayer 216. The air gap 246 may be interposed between thesecond portions of the sidewalls of the neighboring bit line structures224 that extend beyond the storage node contact 240 in the seconddirection.

The air gap 246 may also be interposed between the neighboring bit linestructures 224 in the peripheral region of the substrate 200. However,contact plugs may not be formed in the peripheral region of thesubstrate 200, and thus air spacers may not be formed in the peripheralregion of the substrate 200.

Referring again to FIGS. 7A to 7D, an upper insulation interlayer 252may be formed on the storage node contact 240, the bit line structure224 and the upper spacer 250 in such a manner that that the air gap 246is not filled by the upper insulation interlayer 252. Therefore, the airgap 246 may still be maintained between the neighboring bit linestructures 224 although the bit line structures 224 may be covered withthe upper insulation interlayer 252. For example, the upper insulationinterlayer may comprise silicon nitride.

Thereafter, the capacitor 254 may be formed to penetrate through theupper insulation interlayer 252 and make contact with storage nodecontact 240. For example, the capacitor 254 may be shaped into acylinder and may include a cylindrical lower electrode 254 a, adielectric layer 254 b on a surface of the lower electrode 254 a and anupper electrode 254 c.

More particularly, a mold layer (not shown) may be formed on the upperinsulation interlayer 254. The mold layer and the upper insulationinterlayer 254 may be sequentially removed partially by an etchingprocess, to thereby form an opening (not shown) through which thestorage node contact may be exposed. Then, the cylindrical lowerelectrode 254 a may be formed on bottom and inner surfaces of theopening. The mold layer may be removed from the upper insulationinterlayer 254 after formation of the lower electrode 254 a.

The upper spacer may improve an allowable error range, i.e., a processmargin, of the process for formation of the opening. If the opening ismisaligned with the storage node contact 240, the opening may not exposethe air spacer 250 because the air spacer 250 may be covered with theupper spacer 244. Thus, the lower electrode 254 a may be formed on thestorage node contact 240 despite the misalignment.

In contrast, if the opening is misaligned with the storage node contact240 and no upper spacer is present between the storage node contact 240and the bit line structure 224, the opening may expose the air spacer250 and thus the lower electrode 254 a may formed in the air spacer 250and make contact with the bit line 220 rather than the storage nodecontact 240. That is, the lower electrode 254 a may be incorrectlyformed at a point at which the opening and the air spacer may beconnected to each other.

Embodiment III

FIG. 16 is a perspective view illustrating bit line portion of a dynamicrandom access memory (DRAM) device in accordance with still furtherembodiments of the present inventive concept. The layout of the. DRAMdevice shown in FIG. 16 is the same as the layout shown in FIG. 6. FIG.17A is a cross-sectional view of the DRAM device shown in FIG. 16 cutalong a line A-A′ in FIG. 6 and FIG. 17B is a cross-sectional view ofthe DRAM device shown in FIG. 16 cut along a line B-B′ in FIG. 6. FIG.17C is a cross-sectional view of the DRAM device shown in FIG. 16 cutalong a line C-C′ in FIG. 6.

The DRAM device in accordance with still further embodiments of thepresent inventive concept may have substantially the same structure andconfiguration as the DRAM device in accordance with previously describedembodiments of the present inventive concept, except for the position ofthe air spacer and the shape of the upper spacer. Thus, in the followingdrawings the same reference numerals will be used to refer to the sameor like parts as those shown in the previous drawings.

Referring to FIGS. 16 and 17A to 17C, a substrate 200 including aplurality of active regions and a plurality of device isolation regionsmay be prepared. MOS transistors may be arranged on the cell region ofthe substrate 200 and each of the MOS transistors may include a gateinsulation layer 206 a, a gate electrode 206 b and source and drainelectrodes or regions 208. The gate electrode 206 b may be shaped into aline extending a first direction and may function as a word line 206 inthe MOS transistor. A first insulation interlayer 210 may be foamed onthe substrate 200 to a sufficient thickness to cover the MOStransistors. First and second pad contacts 212 a and 212 b may makecontact with the source and drain electrodes 208, respectively,penetrating through the first insulation interlayer 210. A secondinsulation layer 216 may be positioned on the first insulation layer210.

A bit line contact 218 may make contact with the first pad contact 212 ain the second insulation layer 216. A bit line 220 may be positioned onthe second insulation layer 216 and may make contact with the bit linecontact 218. The bit line may be shaped into a line extending in asecond direction perpendicular to the first direction. A hard maskpattern 222 may be positioned on the bit line 220 and an etch protectionlayer 226 may be arranged on a sidewall of the bit line 220, a surfaceof the hard mask pattern 222 and an upper surface of the secondinsulation interlayer 216. Thus, the sidewall of the bit line 220 may beprotected from being etched in a subsequent process by the etchprotection layer 226.

A storage node contact 240 may be positioned between the neighboring bitline structures 224 in which the bit line 220 and the hard mask pattern222 are stacked. That is, the storage node contact 240 may penetratethrough the second insulation interlayer 216 and may make contact withthe second pad contact 212 b. The storage node contact 240 may have alength shorter than that of the bit line 220 in the second direction.Thus, a first sidewall portion of the bit line structure 224 may facethe storage node contact 240 and a second sidewall portion of the bitline structure 224 that extends beyond the storage node contact 240 mayface a sidewall of neighboring bit line structure 224. That is, the bitline structure 224 may be spaced apart from the storage node contact 240by a first gap distance d1 at the first sidewall portion and may bespaced apart from the neighboring bit line structure by a second gapdistance d2 at the second portion.

An upper spacer 244 a may extend on an upper sidewall of the hard maskpattern 222 in the second direction in such a configuration that anupper sidewall of the storage node contact 240 may be enclosed by theupper spacer 244 a. That is, the upper spacer 244 a may be positioned onthe second sidewall portion of the bit line structure 224 as well as thefirst sidewall portion of the bit line structure 224 as shown in FIG. 16and FIG. 17B. For that reason, the upper spacer 224 a may be aninsulation material such as silicon nitride.

A lower surface of the upper spacer 244 a may be higher than an uppersurface of the bit line 220 of the bit line structure 224, and thus theupper spacer 244 a may not be positioned on a sidewall of the bit line220.

A first space S1 positioned below the upper spacer 244 a and defined bythe storage node contact 240 and the bit line structure 224 may providea void without any kind of thin layers and merely filled with air, tothereby form an air spacer 250 a under the upper spacer 244 a.

In the present example embodiment, the air spacer 250 may verticallyextend from a lower surface of the upper spacer 244 to a lower portionof the bit line structure 224 and a residual or remaining insulationpattern 235 a may be positioned between the second insulation interlayer216 and the storage node contact 240 rather than the air spacer 250. Forexample, the residual insulation pattern 235 a may comprise siliconoxide. An upper surface of the residual insulation pattern 235 a may becoplanar with a lower surface of the bit line 220 and may be confinedbelow the lower surface of the bit line 220. Therefore, the residualinsulation pattern 235 a, which may make contact with the storage nodecontact 240, may not increase the loading capacitance between thestorage node contact 240 and the bit line 220.

The second sidewall portion of the bit line structure 224 may extendbeyond the storage node contact 240 and may face a sidewall ofneighboring bit line structure 224 and may be spaced apart from theneighboring bit line structure by a second gap distance d2. Thus, asecond space S2 defined by the neighboring bit line structures 224 andthe storage node contact 240 may provide a void without any kind of thinlayers and merely filled with air, to thereby form an air gap 246between the neighboring bit line structures 224. Thus, the air spacer250 a and the air gap 246 may be interconnected to each other.

In addition, the air gap 246 may also be interposed between theneighboring bit line structures 224 in the peripheral region of thesubstrate 200, although not shown in figures.

An upper insulation layer 250 may be positioned on the storage nodecontact 240, the upper spacer 244 a, the hard mask pattern 222 and theair gap 246. The air gap 246 may not be filled with the upper insulationlayer 250, to thereby maintain the air gap 246 with the upper insulationlayer 250 thereon. A capacitor 254 may penetrate through the upperinsulation layer 250 and may make electrical contact with the storagenode contact 240. For example, the capacitor 254 may be shaped into acylinder and include a cylindrical lower electrode 254 a, a dielectriclayer 254 b on a surface of the lower electrode 254 a and an upperelectrode 254 c.

FIGS. 18A to 20C illustrate processing steps for a method ofmanufacturing the DRAM device shown in FIGS. 16 and 17A to 17C.

In FIGS. 18A to 20C, the capital letter ‘A’ in each FIG. numberindicates a cross-sectional view cut along the line A-A′ in FIG. 6 andthe capital letter ‘B’ in each FIG number indicates a cross-sectionalview cut along the line B-B′ in FIG. 6. In addition, the capital letter‘C’ in each FIG. number indicates a cross-sectional view cut along theline C-C′ in FIG. 6.

A similar process as described with reference to FIGS. 9A to 9C may beperformed on the substrate 200, and thus a transistor, a firstinsulation interlayer 210, first and second pad contacts 212 a and 212b, a second insulation interlayer 216, a bit line structure 224 and athird insulation interlayer 236 may be formed on the substrate 200.Thereafter, a similar process as described with reference to FIGS. 10Ato 10C may be performed on the resultant structure of the substrate 200,to thereby form a third contact hole 232 penetrating through the thirdand second insulation interlayers 236 and 216.

Then, a sacrificial layer may be formed on a bottom and an innersidewall of the third contact hole 232, on an upper surface of the bitline structure 224, and on the upper surface of the third insulationinterlayer 236. In the present example embodiment, the sacrificial layermay comprise the same material as the third insulation interlayer 236such as silicon nitride.

The sacrificial layer may be partially etched by an anisotropic etchingprocess, to thereby form a preliminary sacrificial spacer 234 on theinner sidewall of the third contact hole 232.

A storage node contact 240 may be formed in the third contact hole 232in which the preliminary sacrificial spacer 234 may be formed, and thusthe preliminary sacrificial spacer 234 may be interposed between thestorage node contact 240 and the bit line structure 224. Therefore, thestorage node contact 240 and the bit line 220 of the bit line structure224 may be electrically insulated from each other by the preliminarysacrificial spacer 234.

As a result of the above processes, a similar structure as illustratedin FIGS. 11A to 11C may be formed on the substrate 200, except that thepreliminary sacrificial spacer 234 may comprise silicon oxide.

Referring to FIGS. 18A to 18C, an upper portion of the preliminarysacrificial layer 234 may be removed downward to a depth, to therebyform a sacrificial spacer 235 interposed between the bit line structure224 and the storage node contact 240. Thus, a gap space 242 a may beformed between an upper portion of the bit line structure 224 and anupper portion of the storage node contact 240. That is, an upper surfaceof the sacrificial spacer 235 may be exposed through the gap space 242a. In the present example embodiment, the removal of the preliminarysacrificial layer 234 may be performed by a wet etching process, therebyreducing and/or minimizing damage to neighboring structures and patternsaround the preliminary sacrificial layer 235.

When the upper portion of the preliminary sacrificial spacer 234 isetched, the third insulation interlayer 236 comprising silicon oxide mayalso be etched simultaneously with the preliminary sacrificial spacer234. Hereinafter, the third insulation interlayer 236 that is partiallyetched will be designated as a new reference numeral 236 a so as todifferentiate the original layer and the etched layer. Thus, the upperportion of the bit line structure 224 may protrude from the etched thirdinsulation interlayer 236 a, as shown in FIG. 18B. In such a case, theupper surface of the third insulation interlayer 236 a may be higherthan the upper surface of the bit line 220 of the bit line structure224.

Therefore, the upper portion of the bit line structure 224 may be spacedapart from the upper portion of the storage node contact 240 by the gapspace 242 a. In a subsequent process, the upper spacer 244 a may beformed in the gap space 242 a and thus the preliminary sacrificial layer234 may be deeply etched to a point at which a lower surface of theupper spacer 244 a may be positioned.

Referring to FIGS. 19A to 19C, an upper spacer layer (not shown) may beformed on the third insulation interlayer 236 a to a sufficientthickness to fill up the gap space 242 a. The upper spacer layer maycomprise a material having etching selectivity with respect to thesacrificial spacer 235 and the third insulation interlayer 236 a. Forexample, the upper spacer layer may comprise an insulation material suchas silicon nitride.

Then, the upper spacer layer may be planarized by a planarizationprocess such as a chemical mechanical polishing (CMP) process or anetch-back process to expose the storage node contact 240, to therebyform the upper spacer 244 a on the upper portion of the hard maskpattern 222 of the bit line structure 224 in such a manner that theupper spacer 244 a may enclose the upper portion of the storage nodecontact 240.

In the present example embodiment, the upper spacer 244 a maycontinuously extend on the upper sidewall of the hard mask pattern 222along the second direction. Thus, if the upper spacer 244 a was formedof a conductive material, the neighboring storage node contacts 240adjacent to each other in the second direction would be electricallyconnected with each other. Therefore, the upper spacer 244 a comprisesan insulation material.

Referring to FIGS. 20A to 20C, the third insulation interlayer 236 a andthe sacrificial spacer 235 may be further etched from the substrate 200in an etching process, preferably a wet etching process. The thirdinsulation interlayer 236 a and the sacrificial spacer 235 may comprisethe same material such as silicon oxide, and thus may be removed by thesame etching process.

In an example embodiment, the third insulation interlayer 236 a may befully removed from the substrate 200 and the sacrificial spacer 235 maybe partially removed from the substrate 200. That is, the sacrificialspacer 235 may remain in a space between the second insulationinterlayer 216 and the storage node contact 240 and between the bit linecontact 218 and the storage node contact 240, to thereby form theresidual insulation pattern 235 a at a lower portion of the storage nodecontact 240. The residual insulation pattern 235 a may improve stabilityof the storage node contact 240.

As a result of the etching process for removal of the sacrificial spacer235 and the third insulation interlayer 236 a, an air spacer may beformed in a first space between the bit line structure 224 and thestorage node contact 240 below the upper spacer 244 a. In addition, asecond space may be formed between second portions of the sidewalls ofthe bit line structures adjacent to each other, to thereby form an airgap 246 between the portions of the neighboring bit line structures 224facing each other and extending beyond the storage node contact 240.

Accordingly, the air spacer 250 a may be interposed between the storagenode contact 240 and the first portion of the sidewall of the bit linestructure 224 and the air gap 246 may be interposed between the secondportions of the sidewalls of the neighboring bit line structures 224extending beyond the storage node contact 240.

The air gap 246 may also be interposed between the neighboring bit linestructures 224 in the peripheral region of the substrate 200. However,contact plugs may not be formed in the peripheral region of thesubstrate 200, and thus the air spacers may not be formed in theperipheral region of the substrate 200.

Referring again to FIGS. 17A to 17C, an upper insulation interlayer 250may be formed on the storage node contact 240, the upper spacer 244 a,the hard mask pattern 222 and the air gap 246 in such a manner that thatthe air gap 246 is not filled with the upper insulation interlayer 250.Thereafter, the capacitor 254 may penetrate through the upper insulationinterlayer 250 and may make contact with storage node contact 240. Forexample, the capacitor 254 may be shaped into a cylinder and include acylindrical lower electrode 254 a, a dielectric layer 254 b on a surfaceof the lower electrode 254 a and an upper electrode 254 c that may beformed substantially by the same process as previously described.

Embodiment IV

FIGS. 21A and 21B are cross-sectional views illustrating a dynamicrandom access memory (DRAM) device in accordance with yet furtherembodiments of the present inventive concept. FIG. 22 is a plan view ofthe DRAM device shown in FIGS. 21A and 21B.

The DRAM device in accordance with yet further embodiments of thepresent inventive concept may have substantially the same structure andconfiguration as the DRAM device in accordance with the previouslydescribed embodiments of the present inventive concept, except for theshape of the air spacer and the lack of an upper spacer. Thus, in thefollowing drawings, the same reference numerals will be used to refer tothe same or like parts as those shown in the previous drawings.

Referring to FIGS. 21A to 21B and 22, a substrate 200 including aplurality of active regions and a plurality of device isolation regionsmay be prepared. MOS transistors may be arranged on the cell region ofthe substrate 200 and each of the MOS transistors may include a gateinsulation layer 206 a, a gate electrode 206 b and source and drainelectrodes or regions 208. The gate electrode 206 b may be shaped into aline extending a first direction and may function as a word line 206 inthe MOS transistor. A first insulation interlayer 210 may be formed onthe substrate 200 to a sufficient thickness to cover the MOStransistors. First and second pad contacts 212 a and 212 b may makecontact with the source and drain electrodes 208, respectively,penetrating through the first insulation interlayer 210. A secondinsulation layer 216 may be positioned on the first insulation layer210.

A bit line contact 218 may make contact with the first pad contact 212 ain the second insulation layer 216. A bit line 220 may be positioned onthe second insulation layer 216 and may make contact with the bit linecontact 218. The bit line may be shaped into a line extending in asecond direction perpendicular to the first direction. A hard maskpattern 222 may be positioned on the bit line 220 and an etch protectionlayer 226 may be arranged on a sidewall of the bit line 220, a surfaceof the hard mask pattern 222 and an upper surface of the secondinsulation interlayer 216. Thus, the sidewall of the bit line 220 may beprotected from being etched in a subsequent process by the etchprotection layer 226.

A storage node contact 240 may be positioned between the neighboring bitline structures 224 in which the bit line 220 and the hard mask pattern222 may be stacked. The storage node contact 240 may have a lengthshorter than that of the bit line 220 in the second direction. Thus, afirst portion of the sidewall of the bit line structure 224 may face thestorage node contact 240 and a second portion of the sidewall of the bitline structure 224 may face a sidewall of neighboring bit line structure224 and extend beyond the storage node contact 240. That is, the bitline structure 224 may be spaced apart from the storage node contact 240by a first gap distance at the first sidewall portion and may be spacedapart from the neighboring bit line structure by a second gap distanceat the second sidewall portion. A spacer 302 may be formed on the secondportion of the sidewalls of the bit line structure 224. The storage nodecontact 240 may penetrate through the third insulation interlayer 236 band the second insulation interlayer 216 and may make contact with thesecond pad contact 212 b.

In the present example embodiment, the storage node contact 240 may beinterposed between the first portions of the sidewalls of theneighboring bit line structures 224 and a third insulation interlayer236 b may be interposed between the second portions of the sidewalls ofthe neighboring bit line structures 224. That is, an air gap may not beprovided between the second portions of the sidewalls of the neighboringbit line structures 224.

Therefore, the storage node contact 240 may be spaced apart from the bitline structure 224 and simultaneously be spaced apart from both of thethird and second insulation interlayers 236 b and 216. That is, thestorage node contact 240 may be spaced apart from surrounding layers bya distance, to thereby form a node gap space enclosing or surroundingthe storage node contact 240. The node gap space may provide a voidwithout any kind of thin spacer materials except for air, to therebydefine an air spacer 300 enclosing the storage node contact 240, asshown in FIG. 22.

More particularly, the air spacer 300 may enclose an upper sidewall ofthe storage node contact 240 and may extend from the upper sidewall to alower sidewall of the storage node contact 240. Therefore, an upperspacer may not be provided with the upper portion of the storage nodecontact 240.

According to the present example embodiment, the air spacer 300 may bepositioned between the first portion of the sidewall of the bit linestructure 224 and the storage node contact 240, and no air gap may beprovided between the second portions of the sidewalls of the bit linestructures 224. In addition, the air gap may not be provided in theperipheral region of the substrate 200.

An upper insulation interlayer 252 may be positioned on the storage nodecontact 240, the hard mask pattern 222 and the air spacer 300. Acapacitor 254 may penetrate through the upper insulation layer 252 andmay make electrical contact with the storage node contact 240. Forexample, the capacitor 254 may be shaped into a cylinder and include acylindrical lower electrode 254 a, a dielectric layer 254 b on a surfaceof the lower electrode 254 a and an upper electrode 254 c.

FIGS. 23A to 24A illustrate processing steps for a method ofmanufacturing the DRAM device shown in FIGS. 21A and 21B. In FIGS. 23Ato 24A, the capital letter ‘A’ in each FIG. number indicates across-sectional view cut along the line A-A′ in FIG. 6.

A similar process as described with reference to FIGS. 9A to 9C may beperformed on the substrate 200, and thus a transistor, a firstinsulation interlayer 210, first and second pad contacts 212 a and 212b, a second insulation interlayer 216 and a bit line structure 224 maybe formed on the substrate 200.

Although not shown in the figures, a bit line spacer may be furtherformed on both sidewalls of the bit line structure 224 after formationof the bit line structure 224.

Thereafter, a third insulation interlayer may be formed on the secondinsulation interlayer 216 to a sufficient thickness to cover the bitline structure 224. The third insulation interlayer and the secondinsulation interlayer 216 may be partially etched, to thereby form anopening through which the second pad contact 212 b may be exposed. Moreparticularly, the bit line spacer exposed through the opening may beremoved from the substrate 200, to thereby form a third contact hole(not shown) penetrating through the third and second insulationinterlayers. Thus, the sidewall of the bit line structure 224 and/or theetch protection layer 226 covering the sidewall of the bit linestructure 224 may be exposed through the third contact hole.

Referring to FIG. 23A, a sacrificial layer (not shown) may be formed ona bottom and an inner sidewall of the third contact hole, on an uppersurface of the bit line structure 224 and on the upper surface of thethird insulation interlayer 236. In the present example embodiment, thesacrificial layer may comprise a material having etching selectivitywith both silicon nitride and silicon oxide. Examples of the materialfor the sacrificial layer may include silicon germanium and polysilicon.The sacrificial layer may be partially removed from the substrate 200 byan anisotropic etching process, to thereby form a sacrificial spacer 235b on the inner sidewall of the third contact hole.

Further, an upper surface of the second pad contact 212 b defining abottom surface of the third contact hole may be partially recessed afterthe formation of the sacrificial spacer 235 b. The recesses of thesecond pad contact 212 b may improve contact characteristics between thesecond pad contact 212 b and the storage node contact 240.

A conductive layer (not shown) may be formed on the third insulationinterlayer and the hard mask pattern 222 to a sufficient thickness tofill up the third contact hole in which the sacrificial spacer 235 b maybe formed. Then, the conductive layer may be planarized by aplanarization process such as a chemical mechanical polishing (CMP)process and an etch-back process until an upper surface of the thirdinsulation interlayer and an upper surface of the hard mask pattern maybe exposed, to thereby form a storage node contact 240 making contactwith the second pad contact 212 b. Thus, the sacrificial spacer 235 bmay be interposed between the storage node contact 240 and the bit linestructure 224.

Referring to FIG. 24A, the sacrificial spacer 235 b may be removed fromthe substrate 200 by a wet etch process, to thereby form the node gapspace between the storage node contact 240 and the bit line structure224. In the present example embodiment, the third insulation interlayermay remain on the substrate 200 in the above wet etch process forremoving the sacrificial spacer 235 b.

The node gap space may provide a void without any kind of thin layersand merely filled with air, to thereby form an air spacer 300surrounding or enclosing the storage node contact 240. Thus, the loadingcapacitance may be reduced between the storage node contact 240 and thebit line structure 224. However, the third insulation interlayer maystill remain in an area between the second portions of the sidewalls ofthe neighboring bit line structures 224, and thus no air gap may beformed between portions of the neighboring bit line structures 224extending beyond the storage node contact 240. In the same way, the airgap may not be formed between the neighboring bit line structures 224 inthe peripheral region of the substrate 200.

Thereafter, as described above with reference to FIGS. 21A, 21B and 22,an upper insulation interlayer 250 may be formed on the storage nodecontact 240, the hard mask pattern 222 and the air spacer 250. Then, thecapacitor 254 may penetrate through the upper insulation interlayer 250and may make contact with storage node contact 240. For example, thecapacitor 254 may be shaped into a cylinder and include a cylindricallower electrode 254 a, a dielectric layer 254 b on a surface of thelower electrode 254 a and an upper electrode 254 c that may be formedsubstantially by the same process as described above.

Embodiment V

FIG. 25A is cross-sectional view illustrating a dynamic random accessmemory (DRAM) device in accordance with other embodiments of the presentinventive concept. FIG. 26 is a plan view illustrating the DRAM deviceshown in FIG. 25A. In FIG. 25A, the capital letter ‘A’ in the FIG.number indicates a cross-sectional view cut along the line A-A′ in FIG.6.

The DRAM device in accordance with other embodiments of the presentinventive concept may have substantially the same structure andconfiguration as the DRAM device in accordance with the previouslydescribed embodiments of the present inventive concept, except for theposition and shape of the air spacer and the lack of an upper spacer.Thus, in the following drawings, the same reference numerals will beused to refer to the same or like parts as those shown in the previousdrawings.

Referring to FIGS. 25A and 26, a substrate 200 including a plurality ofactive regions and a plurality of device isolation regions may beprepared. MOS transistors may be arranged on the cell region of thesubstrate 200 and each of the MOS transistors may include a gateinsulation layer 206 a, a gate electrode 206 b and source and drainregions and/or electrodes 208. The gate electrode 206 b may be shapedinto a line extending a first direction and may function as a word line206 in the MOS transistor. A first insulation interlayer 210 may beformed on the substrate 200 to a sufficient thickness to cover the MOStransistors. First and second pad contacts 212 a and 212 b may makecontact with the source and drain electrodes 208, respectively,penetrating through the first insulation interlayer 210. A secondinsulation layer 216 may be positioned on the first insulation layer210.

A bit line contact 218 may make contact with the first pad contact 212 ain the second insulation layer 216. A bit line 220 may be positioned onthe second insulation layer 216 and may make contact with the bit linecontact 218. The bit line 220 may be shaped into a line extending in asecond direction substantially perpendicular to the first direction. Ahard mask pattern 222 may be positioned on the bit line 220 and an etchprotection layer 226 may be arranged on a sidewall of the bit line 220,a surface of the hard mask pattern 222 and an upper surface of thesecond insulation interlayer 216. Thus, the sidewall of the bit line 220may be protected from being etched in a subsequent process by the etchprotection layer 226.

A storage node contact 240 may be positioned between the neighboring bitline structures 224 in which the bit line 220 and the hard mask pattern222 may be stacked. The storage node contact 240 may have a lengthshorter than that of the bit line 220 in the second direction. Thus, afirst portion of the sidewall of the bit line structure 224 may face thestorage node contact 240 and a second portion of the sidewall of the bitline structure 224 may extend beyond the storage node contact 240 andmay face a sidewall of neighboring bit line structure 224. That is, thebit line structure 224 may be spaced apart from the storage node contact240 by a first gap distance at the first sidewall portion and may bespaced apart from the neighboring bit line structure by a second gapdistance at the second sidewall portion.

The storage node contact 240 may be interposed between the firstportions of the sidewalls of the neighboring bit line structures 224 anda third insulation interlayer 236 b may be interposed between the secondportions of the sidewalls of the neighboring bit line structures 224that extend beyond the storage node contact 240. That is, no air gap maybe provided between the second portions of the sidewalls of theneighboring bit line structures 224.

As shown in FIG. 26, the storage node contact 240 may be separated andspaced apart from the sidewalls of the neighboring bit line structures224 in the first direction while making contact with the second andthird insulation interlayers 216 and 236 in the second direction. Thatis, the storage node contact 240 may be spaced apart from the bit linestructure 224 by a distance, to thereby form a gap space between thestorage node contact 240 and the bit line structure 224. The gap spacemay provide a void without any kind of thin spacer materials except forair, to thereby form an air spacer 302 that separates and electricallyinsulates the storage node contact 240 from the bit line structure 224and extends in the second direction. The air spacer 302 may extend fromthe upper sidewall to a lower sidewall of the storage node contact 240,and thus no upper spacer may be provided with the upper portion of thestorage node contact 240. In other words, the air spacer 302 may extendalong an entirety of the sidewalls of the storage node contact 240(e.g., from top to bottom) in some embodiments.

Also, the air spacer 302 may be interposed between the storage nodecontact 240 and the bit line structure 224 and may extend along a lengthon the sidewall of the bit line structure in the second direction. Inaddition, the air spacer 302 may vertically extend from the uppersidewall to a lower sidewall of the storage node contact 240.

Thus, the DRAM devices according to other embodiments of the presentinventive concept may include the air spacer interposed between the bitline structure and the storage node contact, and may not include an airgap between the neighboring bit line structures.

The air spacer may also be interposed between the neighboring bit linestructures in the peripheral region of the substrate, while no air gapmay be provided between the neighboring bit line structures in theperipheral region of the substrate.

An upper insulation interlayer 252 may be positioned on the storage nodecontact 240, the hard mask pattern 222 and the air spacer 300. Acapacitor 254 may penetrate through the upper insulation layer 252 andmay make electrical contact with the storage node contact 240. Forexample, the capacitor 254 may be shaped into a cylinder and include acylindrical lower electrode 254 a, a dielectric layer 254 b on a surfaceof the lower electrode 254 a and an upper electrode 254 c.

FIGS. 27A to 29A illustrate processing steps for a method ofmanufacturing the DRAM device shown in FIG. 25A. In FIGS. 23A to 29A,the capital letter ‘A’ in each FIG number indicates a cross-sectionalview cut along the line A-A′ in FIG. 6.

The same process as described with reference to FIGS. 9A to 9C may beperformed on the substrate 200, and thus a transistor, a firstinsulation interlayer 210, first and second pad contacts 212 a and 212b, a second insulation interlayer 216 and a bit line structure 224 maybe formed on the substrate 200.

Referring to FIG. 27A, a sacrificial layer (not shown) may be formed onthe sidewall of the bit line structure 224 and on the second insulationinterlayer 216. The sacrificial layer may comprise a material havingetching selectivity with respect to both of silicon nitride and siliconoxide such as silicon germanium or polysilicon.

The sacrificial layer may be partially removed from the secondinsulation interlayer by an anisotropic etching process, to thereby forma sacrificial spacer 310 on the sidewall of the bit line structure 224.In the present example embodiment, the sacrificial spacer 310 may alsobe formed on the sidewall of the bit line structure 224 in theperipheral region of the substrate 200.

Referring to FIG. 28A, a third insulation interlayer may be formed onthe second insulation interlayer 216 to a sufficient thickness to fillup the space between the sacrificial spacers 310. Then, the thirdinsulation interlayer may be planarized by a planarization process suchas a CMP process and an etch-back process until an upper surface of thebit line structure 224 may be exposed.

The third and second insulation interlayers may be partially andsequentially removed from the substrate 200, to thereby form a contacthole 232 through which the second pad contact 212 b may be exposed.Thus, the sacrificial spacer 310 may be exposed through the contact hole232.

Thereafter, an upper surface of the second pad contact 212 b, whichdefines a bottom of the contact hole 232, may be partially recessed, tothereby improve contact characteristics between the second pad contact212 b and the storage node contact 240.

Referring to FIG. 29A, a conductive layer (not shown) may be formed onthe third insulation interlayer and the hard mask pattern 222 to asufficient thickness to fill up the contact hole 232 in which thesacrificial spacer 310 may be formed. Then, the conductive layer may beplanarized by a planarization process such as a chemical mechanicalpolishing (CMP) process and an etch-back process until an upper surfaceof the third insulation interlayer and an upper surface of the hard maskpattern may be exposed, to thereby form a storage node contact 240making contact with the second pad contact 212 b. Thus, the sacrificialspacer 310 may be interposed between the storage node contact 240 andthe bit line structure 224.

The sacrificial spacer 310 may be removed from the substrate 200 by awet etch process, to thereby form a gap space between the storage nodecontact 240 and the bit line structure 224. In the present exampleembodiment, the third insulation interlayer may remain on the substrate200 in the above wet etch process for removing the sacrificial spacer310.

The gap space may provide a void without any kind of thin layers andmerely filled with air, to thereby form an air spacer 312 interposedbetween the storage node contact 240 and the bit line structure 224.Thus, the loading capacitance may be sufficiently reduced between thestorage node contact 240 and the bit line structure 224. In addition,the air spacer 312 may also be formed between the neighboring bit linestructures 224 in the peripheral region of the substrate 200.

However, the third insulation interlayer may still remain in an areabetween the second portions of the sidewalls of the neighboring bit linestructures 224, and thus no air gap may be formed between the portionsof neighboring bit line structures 224 that extend beyond the storagenode contact 240 in the second direction. In the same way, the air gapmay not be formed between the neighboring bit line structures 224 in theperipheral region of the substrate 200.

Thereafter, as described above with reference to FIGS. 25A and 26, anupper insulation interlayer 252 may be formed on the storage nodecontact 240, the hard mask pattern 222 and the air spacer 312. Then, thecapacitor 254 may penetrate through the upper insulation interlayer 252and may make contact with storage node contact 240. For example, thecapacitor 254 may be shaped into a cylinder and include a cylindricallower electrode 254 a, a dielectric layer 254 b on a surface of thelower electrode 254 a and an upper electrode 254 c that may be formedsubstantially by the same process as described above.

Embodiment VI

FIG. 30A is cross-sectional view illustrating a dynamic random accessmemory (DRAM) device in accordance with still other embodiments of thepresent inventive concept. The capital letter ‘A’ in the FIG. numberindicates a cross-sectional view cut along the line A-A′ in FIG. 6.

The DRAM device in accordance with still other embodiments of thepresent inventive concept may have substantially the same structure andconfiguration as the DRAM device in accordance with the previouslydescribed embodiments of the present inventive concept, except for theaddition of an additional spacer 320 on the bit line structure 224, thesecond insulation interlayer 216, the bit line contact and the thirdinsulation interlayer. Thus, in the following drawings, the samereference numerals will be used to refer to the same or like parts asthose shown in the previous drawings.

Referring to FIG. 30A, the additional spacer 320 may face the storagenode contact 240 and may surround and/or enclose a stacked structureincluding the second insulation interlayer 216, the bit line 220 and thehard mask pattern 222. The additional spacer 320 may comprise aninsulation material such as silicon nitride.

The additional spacer 320 may have a relatively narrow thickness on thebit line structure 224, and an upper spacer 244 may be positioned on theupper sidewall of the addition spacer 320. An air spacer 250 may beprovided below the upper spacer 244, such that the upper spacer 244defines an upper boundary of the air spacer 250.

Hereinafter, the process steps for a method of manufacturing the DRAMdevice shown in FIG. 30A will be described.

The same process as described with reference to FIGS. 9A to 9C may beperformed on the substrate 200, and thus a transistor, a firstinsulation interlayer 210, first and second pad contacts 212 a and 212b, a second insulation interlayer 216 and a bit line structure 224 maybe formed on the substrate 200. Then, a third insulation interlayerhaving a third contact hole may be formed on the second insulationinterlayer 216. A spacer layer may be formed on the third insulationinterlayer to a sufficient thickness to fill up the third contact hole.For example, the spacer layer may comprise silicon nitride. The spacerlayer may be formed into a sacrificial spacer in the third contact holeby an anisotropic etching process.

Thereafter, the same process as described with reference to FIGS. 10A to15D may be performed on the resultant structure on the substrate 200, tothereby form the DRAM device shown in FIG. 30A.

According to the present example embodiment, the thin additional spacer320 may be further provided with the DRAM device and thus the additionalspacer and the air spacer may function as a dielectric layer between thestorage node contact and the bit line structure in the DRAM device.

Embodiment VII

FIG. 31A is cross-sectional view illustrating a dynamic random accessmemory (DRAM) device in accordance with yet other embodiments of thepresent inventive concept. FIG. 32 is a perspective view illustrating abit line structure of the DRAM device shown in FIG. 31A. In FIG. 31A,the capital letter ‘A’ in the FIG. number indicates a cross-sectionalview cut along the line A-A′ in FIG. 6.

The DRAM device in accordance with yet other embodiments of the presentinventive concept may have substantially the same structure andconfiguration as the DRAM device in accordance with the previouslydescribed embodiments of the present inventive concept, except for theshape of the upper spacer. Thus, in the following drawings, the samereference numerals will be used to refer to the same or like parts asthose shown in the previous drawings.

Referring to FIGS. 31A and 32, a substrate 200 including a plurality ofactive regions and a plurality of device isolation regions may beprepared. MOS transistors may be arranged on the cell region of thesubstrate 200 and each of the MOS transistors may include a gateinsulation layer 206 a, a gate electrode 206 b and source and drainelectrodes 208. The gate electrode 206 b may be shaped into a lineextending a first direction and may function as a word line 206 in theMOS transistor. A first insulation interlayer 210 may be formed on thesubstrate 200 to a sufficient thickness to cover the MOS transistors.First and second pad contacts 212 a and 212 b may make contact with thesource and drain electrodes 208, respectively, penetrating through thefirst insulation interlayer 210. A second insulation layer 216 may bepositioned on the first insulation layer 210.

A bit line contact 218 may make contact with the first pad contact 212 ain the second insulation layer 216. A bit line 220 may be positioned onthe second insulation layer 216 and may make contact with the bit linecontact 218. The bit line may be shaped into a line extending in asecond direction perpendicular to the first direction. A hard maskpattern 222 may be positioned on the bit line 220 and an etch protectionlayer 226 may be arranged on a sidewall of the bit line 220, a surfaceof the hard mask pattern 222 and an upper surface of the secondinsulation interlayer 216. Thus, the sidewall of the bit line 220 may beprotected from being etched in a subsequent process by the etchprotection layer 226.

A storage node contact 240 may be positioned between the neighboring bitline structures 224 in which the bit line 220 and the hard mask pattern222 are sequentially stacked. The storage node contact 240 may penetratethrough the second insulation interlayer 216 and may make contact withthe second pad contact 212 b. The storage node contact 240 may have alength shorter than that of the bit line structure 224 in the seconddirection. Thus, a first sidewall portion of the bit line structure 224may face the storage node contact 240 and a second sidewall portion ofthe bit line structure 224 may extend beyond the storage node contact240 and face a sidewall of neighboring bit line structure 224. That is,the bit line structure 224 may be spaced apart from the storage nodecontact 240 by a first gap distance d1 at the first sidewall portion andmay be spaced apart from the neighboring bit line structure by a secondgap distance d2 at the second sidewall portion. An upper sidewall of thestorage node contact 240 may make contact with the upper spacer 322.That is, the upper spacer 322 may be interposed between the upperportion of the storage node contact 240 and the upper portion of the bitline structure 224.

An upper spacer 322 may extend along an upper sidewall of the hard maskpattern 222 that is covered with the etch protection layer 226 in thesecond direction. That is, the upper spacer 322 may be positioned on thesecond sidewall portions of the bit line structure 224 that extendbeyond the storage node contact 240 as well as the first sidewallportions of the bit line structure 224 that are adjacent to the storagenode contact 240. For that reason, the upper spacer 322 may be aninsulation material such as silicon nitride. In contrast to the DRAMdevice shown in FIG. 16, the storage node contact 240 may not beenclosed or surrounded by the upper spacer 322.

A first space S1 positioned below the upper spacer 322 and defined bythe storage node contact 240 and the bit line structure 224 may providea void without any kind of thin layers and merely filled with air, tothereby form an air spacer 330 under the upper spacer 322. In thepresent example embodiment, the air spacer 330 may vertically extendfrom a lower surface of the upper spacer 244 to a lower portion of thebit line structure 224, and a residual insulation pattern 235 a may bepositioned between the second insulation interlayer 216 and the storagenode contact 240 in place of the air spacer 330. For example, theresidual insulation pattern 235 a may comprise silicon oxide. An uppersurface of the residual insulation pattern 235 a may be coplanar with alower surface of the bit line 220 and may be lower than the lowersurface of the bit line 220. Therefore, the residual insulation pattern235 a, which may make contact with the storage node contact 240, may notincrease the loading capacitance between the storage node contact 240and the bit line 220.

The second sidewall portion of the bit line structure 224 may face asidewall of a neighboring bit line structure 224 and may be spaced apartfrom the neighboring bit line structure by a second gap distance d2.Thus, a second space S2 defined by the neighboring bit line structures224 and the storage node contact 240 may provide a void without any kindof thin layers and merely filled with air, to thereby form an air gap332 between the neighboring bit line structures 224. Thus, the airspacer 330 and the air gap 332 may be interconnected to each other.Particularly, the upper spacer 322 may not be formed on the uppersidewall of the storage node contact 240 in the second space S2 ascompared with the upper spacer 244 a of the DRAM device shown in FIG.16.

In addition, the air gap 332 may also be interposed between theneighboring bit line structures 224 in the peripheral region of thesubstrate 200, although not shown in figures.

An upper insulation layer (not shown) may be positioned on the storagenode contact 240, the upper spacer 322, the hard mask pattern 222 andthe air gap 332. The air gap 332 may not be filled with the upperinsulation layer, to thereby maintain the air gap 332 despite of theupper insulation layer. As such, the upper insulation layer may definean upper boundary of the air gap between neighboring bit linestructures. A capacitor (not shown) may penetrate through the upperinsulation layer and may make electrical contact with the storage nodecontact 240. For example, the capacitor may be shaped into a cylinderand include a cylindrical lower electrode, a dielectric layer on asurface of the lower electrode and an upper electrode.

FIGS. 33A to 35A illustrate processing steps for a method ofmanufacturing the DRAM device shown in FIG. 31A. In FIGS. 33A to 35A,the capital letter ‘A’ in each FIG number indicates a cross-sectionalview cut along the line A-A′ in FIG. 6.

The same process as described with reference to FIGS. 9A to 9C may beperformed on the substrate 200, and thus a transistor, a firstinsulation interlayer 210, first and second pad contacts 212 a and 212b, a second insulation interlayer 216 and a bit line structure 224 maybe formed on the substrate 200.

Referring to FIG. 33A, a preliminary sacrificial spacer 320 s may beformed on the sidewall of the bit line structure 224. For example, thepreliminary sacrificial spacer 320 s may comprise silicon germanium orpolysilicon. The preliminary sacrificial spacer 320 s may be formed onthe sidewall of the bit line structure 224 in the peripheral region aswell as the cell region of the substrate 200. Thereafter, a thirdinsulation interlayer may be formed on the second insulation interlayer216 to a sufficient thickness to cover the bit line structure 224 andthe preliminary sacrificial spacer 320 s. Then, the third insulationinterlayer 236 may be planarized by a planarization process until anupper surface of the bit line structure 224 and an upper surface of thepreliminary sacrificial spacer 320.

Referring to FIG. 34A, an upper portion of the preliminary sacrificiallayer 320 s may be removed downward along the second direction, tothereby form a gap space (not shown) between an upper portion of thethird insulation interlayer 236 and an upper portion of the bit linestructure 224. The gap space may have a depth from the upper surface ofthe preliminary sacrificial layer 320 s and may extend in the seconddirection. The residual portions of the preliminary sacrificial layer320 s may remain on the bit line structure 224, to thereby form asacrificial spacer 320 a extending along the second direction inparallel with the bit line structure 224. An upper surface of thesacrificial spacer 320 a may be higher than an upper surface of the bitline 220 of the bit line structure 224. For example, preliminarysacrificial layer 320 s may be removed from the bit line structure 224by a wet etching process.

Thereafter, a spacer layer (not shown) may be formed on the thirdinsulation interlayer to a sufficient thickness to fill the gap spacebetween an upper portion of the third insulation interlayer 236 and anupper portion of the bit line structure 224. Then, the spacer layer maybe planarized by a planarization process, such as a CMP process, and anetch-back process, to thereby form the upper spacer 322 in the gapspace. Therefore, the sidewall of the bit line structure 244 may becovered with both the upper spacer 322 and the sacrificial spacer 320 a.

Referring to FIG. 35A, the third insulation interlayer and the secondinsulation interlayer 216 may be partially and sequentially removed fromthe substrate 200, to thereby form a contact hole through which thesecond pad contact 212 b may be exposed. Thus, both the sacrificialspacer 320 a and the upper spacer 322 may be exposed in the contacthole.

A conductive layer (not shown) may be formed on the third insulationinterlayer to a sufficient thickness to fill up the contact hole. Then,the conductive layer may be planarized by a planarization process untilan upper surface of the third insulation interlayer may be exposed, tothereby form a storage node contact 240 making contact with the secondpad contact 212 b in the contact hole.

Thereafter, the third insulation interlayer may be removed from theinsulation interlayer 216 by a dry etching process and/or a wet etchingprocess, more preferably, by a wet etching process. For the removal ofthe third insulation interlayer, a second space S2 may be formed betweenthe second portions of the sidewalls of the neighboring bit linestructures 224. Thus, the second space S2 may be defined by theneighboring bit line structures 224 and the storage node contact 240 andmay provide a void without any kind of thin layers and merely filledwith air, to thereby form an air gap 332 between the neighboring bitline structures 224. In addition, the upper spacer 322 and thesacrificial spacer 320 a may also be exposed and/or in contact with tothe second space S2.

The sacrificial spacer 320 a may be partially removed from the substrate200 by a wet etching process, thereby form a first space S1 below theupper spacer 322. The first space S1 may be defined by the bit linestructure, the storage node contact 240 and the upper spacer 322 and mayprovide a void without any kind of thin layers and merely filled withair, to thereby define an air space 330 between the line structure 224and the storage node contact 240. In the present example embodiment, theair spacer 330 may extend from the bottom surface of the upper spacer322 to a lower portion of the bit line structure 224. Laterallyextending portions of the mask 226 may define a lower boundary of theair spacer 330.

In addition, the air gap may also be formed between the neighboring bitline structures 224 in the peripheral region as well as cell region ofthe substrate 200.

The same process as described with reference to FIG. 31A may beperformed on the resultant structure on the substrate 200, to therebyfaun an upper insulation interlayer 252 on the storage node contact 240,the upper spacer 322, the hard mask pattern 222 and the air gap 332 insuch a manner that that the air gap 332 is not filled with the upperinsulation interlayer 252. Thereafter, the capacitor 254 may penetratethrough the upper insulation interlayer 252 and may make contact withstorage node contact 240. The capacitor 254 may be formed on the upperinsulation interlayer 252 in the same process as described above.

According to example embodiments of the present inventive concept,conductive structures may be formed on a substrate with a high degree ofintegration and may be operated at high speed. In some embodiments, theconductive structures may be used in a wiring structure for a DRAMdevice.

The foregoing is illustrative of example embodiments and is not to beconstrued as limiting thereof. Although a few example embodiments havebeen described, those skilled in the art will readily appreciate thatmany modifications are possible in the example embodiments withoutmaterially departing from the novel teachings and advantages of thepresent invention. Accordingly, all such modifications are intended tobe included within the scope of the present invention as defined in theclaims. Therefore, it is to be understood that the foregoing isillustrative of various example embodiments and is not to be construedas limited to the specific example embodiments disclosed, and thatmodifications to the disclosed example embodiments, as well as otherexample embodiments, are intended to be included within the scope of theappended claims.

1-10. (canceled)
 11. A method of fabricating an integrated circuitdevice, the method comprising: forming first and second conductivestructures on a substrate spaced apart from one another in a firstdirection and extending in a second direction substantiallyperpendicular to the first direction; forming a contact plug between thefirst and second conductive structures and spaced apart from the firstand second conductive structures in the first direction by respectiveair gaps on opposite sides of the contact plug, the air gaps definingfirst and second air spacers that electrically insulate the contact plugfrom the first and second conductive structures, respectively; andforming an upper insulation layer on the first and second air spacersand the first and second conductive structures.
 12. The method of claim11, further comprising: forming first and second upper spacers above thefirst and second air spacers, respectively, the first and second upperspacers separating respective sidewalls of the contact plug fromsidewalls of the first and second conductive structures adjacentthereto, wherein the first and second upper spacers define an upperboundary of the first and second air spacers therebelow.
 13. The methodof claim 11, wherein forming the contact plug comprises: forming aninsulation layer on the first and second conductive structures;partially removing the insulation layer to form a contact hole throughwhich sidewalls of the first and second conductive structures areexposed; forming sacrificial spacers in the contact hole on thesidewalls of the first and second conductive structures exposed throughthe contact hole; forming the contact plug in the contact hole includingthe sacrificial spacers therein; and then removing the sacrificialspacers from the sidewalls of the conductive structures such that thecontact plug is spaced apart from the sidewalls of the first and secondconductive structures by the air gaps defining the first and second airspacers.
 14. The method of claim 13, further comprising: removing theinsulation layer from the substrate after forming the contact plug andbefore removing the sacrificial spacers. 15-29. (canceled)
 30. A methodof fabricating an integrated circuit device, the method comprising:forming a structure on a substrate, the structure including at least onepad contact; forming a plurality of bit line structures on the substratespaced apart from one another along a first direction, the bit linestructures extending in a second direction substantially perpendicularto the first direction; forming respective contact plugs betweenneighboring ones of the bit line structures and spaced apart therefromby first gaps in the first direction, the first gaps defining respectiveair spacers that electrically insulate the neighboring ones of the bitline structures from the respective contact plugs therebetween; andforming an upper insulation layer covering the air spacers and the bitline structures.
 31. The method of claim 30, wherein forming therespective contact plugs comprises: forming an insulation layer on thesubstrate to cover the bit line structures; partially removing theinsulation layer to form contact holes through which sidewalls of thebit line structures are exposed; forming sacrificial spacers on thesidewalls of the bit line structures exposed through the contact holes;forming the respective contact plugs in the contact holes including thesacrificial spacers therein; and then at least partially removing thesacrificial spacers from the sidewalls of the bit line structures suchthat the contact plugs and the sidewalls of the bit line structures arespaced apart from each other by the first gaps to define the airspacers.
 32. The method of claim 31, wherein forming the contact plugsfurther comprises: removing an upper portion of at least one of thesacrificial spacers to provide an upper gap space defined by a remainingportion of the at least one of the sacrificial spacers; and forming anupper spacer in the upper gap space, the upper spacer separating anupper portion of a respective one of the contact plugs adjacent theretofrom an upper portion of a respective one of the bit line structuresadjacent thereto in such a manner that the respective one of the contactplugs is surrounded by the upper spacer.
 33. The method of claim 32,wherein the upper spacer comprises one of a solid insulating materialand a conductive material.
 34. The method of claim 32, wherein the upperspacer comprises a material having etching selectivity with respect tothe sacrificial spacers.
 35. The method of claim 31, wherein forming thecontact plugs further comprises: removing the insulation layer from thesubstrate before removing the sacrificial spacers such that portions ofthe neighboring ones of the bit line structures extending beyond therespective contact plugs in the second direction are spaced apart fromone another by respective second gaps along the first direction, thesecond gaps defining respective air gaps between the portions of theneighboring ones of the bit line structures.
 36. The method of claim 31,wherein forming the contact plugs comprises: forming sacrificial spacerson sidewalls of the bit line structures; forming an insulation layer onthe substrate to a thickness sufficient to cover the bit linestructures; partially removing the insulation layer from the substrateto form contact holes through which portions of the sacrificial spacersare exposed; forming the respective contact plugs in the contact holessuch that the sacrificial spacers contact the respective contact plugs;and removing the sacrificial spacers such that the respective contactplugs and the bit line structures adjacent thereto are spaced apart fromone another by the first gaps to define the air spacers between thecontact plugs and the bit line structures.
 37. The method of claim 36,wherein forming the contact plugs further comprises: removing an upperportion of at least one of the sacrificial spacers to form an upper gapspace defined by a remaining portion of the at least one of thesacrificial spacers; and forming an upper spacer in the upper gap space,the upper spacer extending on a sidewall of an upper portion of arespective one of the bit line structures in the second direction. 38.The method of claim 37, wherein the upper spacer comprises an insulationmaterial.